This invention relates to gas mixers and reactors. In another aspect, this invention relates to gas burners. Still another aspect of this invention relates to a novel method and means for controlling the combustion of gaseous components. In still another aspect, this invention relates to a novel method and means for converting sulfur containing gases into sulfur. In another aspect, this invention relates to an acid gas burner for a plant for the recovery of sulfur from hydrogen sulfide.
Apparatus for reacting and combusting gaseous components wherein the relative quantities of gaseous reactants must be precisely controlled, such as substoichiometric burners, require not only means to effect an efficient mixing operation but sufficient flow control features to allow proper metering of the reactant materials. Most gas burners do not provide these features. Furthermore, conventional such burners and the like are subject to heat and/or chemical deterioration and do not provide a good visual contact with the combustion zone.
A conventional chemical process which requires a closely controlled gaseous feed is the so-called Claus process for converting hydrogen sulfide into elemental sulfur. The Claus process was developed in Germany in the late 19th Century and has undergone improvement through the years. The Claus process is described on pages 353 and 354 of Volume 19 of Kirk -- Othmer Encyclopedia of Chemical Technology, 2nd Edition, 1969. In the process, hydrogen sulfide is conventionally fed into a combustion chamber and burned in such a manner that one-third of the volume of hydrogen sulfide is converted into sulfur dioxide. Alternately, a feed stream of concentrated hydrogen sulfide is split such that one-third is completely oxidized to sulfur dioxide and later combined with the remaining concentrated stream. Generally the products of combustion from the combustion chamber are initially cooled and then passed through a catalyst packed converter in which the following reaction occurs: EQU 2H.sub.2 S + SO.sub.2 = 3S+ 2H.sub.2 O
various combustion devices and gas reactors have been developed to convert the hydrogen sulfide into the SO.sub.2 - H.sub.2 S feed stream for the Claus process. These devices are commonly known as acid gas burners. These acid gas burners admix a rich H.sub.2 S gas stream with air to cause the proper reaction. The acid gas burner which is presently widely utilized comprises a burner tube having one end extending into the combustion chamber with a hemispherical cap mounted on the end thereof having a convex surface facing the combustion chamber. The cap has concentric sets of holes therethrough to provide diverging streams of the flow of the gas from the tube into the combustion chamber. Part of the H.sub.2 S gas stream that is passed through these concentric sets of holes is burned primarily to SO.sub.2. The burner is generally mounted through the wall of the combustion chamber and extends through a larger pipe. Air is fed through the annular space between the larger pipe and the burner. The air and acid gas mix adjacent the cap and are ignited at a high temperature (as high as 2000.degree. to 2500.degree.F). The acid gas is highly corrosive and the high temperature reaction of the acid gas on the cap causes deformation of the burner cap and corrosion which in turn results in high pressure drop and back pressure in the system. Furthermore, this deleterious action results in the inability to properly control the substoichiometric reaction. Additionally, this type of burner is not a good mixer of the gaseous fluids and is not necessarily stable over a full range of operation.
Improvements have been attempted in acid gas burners and similar gas reactors to provide for a thorough admixing of the gaseous reactants but yet diminish both thermal and chemical deterioration of metal parts. An example of such apparatus is disclosed in U.S. Pat. No. 3,782,884.